The present invention relates generally to flexible liner baby nursing bottles of the general type having an open ended shell body and flexible liner and more particularly to apparatus for varying the volume of the liner to expel unwanted air and to prevent reentry of air through the nipple. The invention also relates to a method for using the apparatus to vary the volume of the flexible liner of the baby nursing bottle.
A common problem generally associated with nursing baby bottles is the presence of air in the bottle and which air can be the cause of gas, coughing, or other gastric intestinal disturbances. This problem is generally associated with a conventional baby nursing bottles and has been somewhat solved by the usage of flexible liner baby nursing bottles of the general type in which a flexible liner is supported by a cylindrical, open ended shell body and a nipple which holds the liner to the shell. One such type is commonly known as the "Playtex baby nurser" manufactured by the Playtex Corporation. These nursing baby bottles have become widely used and accepted because the flexible liner decreases in volume as the infant feeds thereby permitting the infant to receive formula or other liquids without sucking in air.
Baby nursing bottles, such as the above-referenced type, initially require that air in the chamber formed by the nipple and the liner cavity be expelled manually prior to the start of feeding. One typical and common method of expelling air is for the user to insert his or her fingers into the open end of the shell body and push on the liner until all of the air is expelled and only liquid remains in the liner and nipple portion. While air may be expelled in this manner for a full bottle, as the amount of liquid in the bottle diminishes the liner must be pushed further into the shell from the open lower end of the shell body until the user's fingers can no longer reach the liner to compress the liner and liquid contained therein to expel any captured air.
Another common problem generally associated with flexible liner baby nursing bottles is the reentry of air into the liner after the bottle has been put aside, particularly in an upright position such as might be the case when the baby is being burped or otherwise attended to. The weight of the liquid in the liner tends to pull the liner downward drawing air into the liner through the nipple. Air may also be drawn into the liner when the baby stops sucking for a period of time since the vacuum created by the sucking is removed.
One attempt to solve the problem of air reentry is the use of a mating cap that contacts or compresses the nipple to form a seal. However, the mating cap seldom works efficiently which allows air to reenter the liner of the baby nursing bottle and requires that a user interrupt the infant feeding to attempt to expel the air once again. Additionally, the mating cap does not solve the problem of expelling air which already exists in the liner, its difficulty and usage during the infant feeding process and must generally be sterilized prior to use since it comes into contact with the nipple of the bottle.
It is desirable therefore to provide apparatus and a related method for use with a flexible liner baby nursing bottle which generally overcomes the problems of expelling air from the bottle described above.
It is a general aim therefore of the present invention to provide a method and apparatus which may be used with a flexible liner baby nursing bottle to vary the volume of the liner containing the formula or the like.
It is another aim of the present invention to provide a method and apparatus for use with a flexible liner baby nursing bottle which expels air from the liner.
It is another aim of the present invention to provide a method and apparatus for use with a flexible liner baby nursing bottle which prevents the reentry of air into the liner when the bottle is set aside during interruption of the nursing process.
It is yet a further aim of the present invention to provide a method and apparatus for use with a flexible liner baby nursing bottle that is inexpensive, easy to use and hygienically safe.